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The Fike Micromist system is a self contained, single fluid, pre-engineered water mist fire suppression system for total compartment protection of machinery spaces and compartmental gas turbine generators.
MICROMIST OPERATING PRINCIPLE
Water is an outstanding fire suppression agent due to its high heat capacity and latent heat of vaporization. The Fike Micromist system nozzle uses a plate to slice the small jets of water that flow through the nozzle orifice. The resulting water mist contains a variety of droplet sizes. The larger droplets produced by the nozzle provide the necessary energy and momentum to carry the smaller droplets to the base of the fire where the mist vaporizes and extinguishes the fire. The simple theory behind this development is that a large amount of small droplets have a greater surface area than the same volume of large droplets, therefore absorb more heat.
Water mist systems extinguish fires using the following basic principles:
- Cooling – As the mist is converted into vapor it removes heat from the fire source.
- Inerting – As the water mist turns to steam it expands approximately 1700 times, forcing oxygen away from the flame front, thus denying it the oxygen necessary to support combustion.(localized inert environment)
- Wetting – Primarily for incidental class A fires; wetting of the surface helps extinguish the fire as well as contain it.
APPLICATIONS
The system will very effectively extinguish flammable liquid pool fires as well as spray fires which could ignite from a ruptured hose or pipe in a process using flammable liquids. Micromist applications include, but are not limited to, the following:
- compartmentalized gas turbine generators
- engine test cells
- generator rooms
- machinery spaces with incidental storage of flammable liquids
- oil pumps
- lubrication skids
- oil reservoirs
- diesel emergency rooms
- fuel filters
- dipping, electrostatic coating or cleaning processes using flammable liquids
- gear boxes
- drive shafts
- engine drive generators
- chemical processes
- flammable or combustible liquid pumps piping or con-tainers under pressure such as may be used with hydraulic pumping equipment
SYSTEM OPERATION
When a fire condition is detected in the protected hazard, the Cheetah control panel sends a signal to the solenoid releasing module (SRM) to operate the Micromist suppression system. The Micromist system contains nitrogen cylinder(s) and a water cylinder. The nitrogen storage cylinder provides pressure to drive the water to the system nozzles. When the system is operated, valves on the nitrogen tanks open and the resulting air pressure flows through a pressure regulating valve (PRV) which regulates the pressure to 320 psi(22 Bar). This pressure drives the water through the opened water valve and to the system nozzles. The Micromist system uses relatively short pulses of water called cycling to aid in the extinguishment of fires as well as minimize the property damage associated with a continuous discharge.
SYSTEM COMPONENTS
The Cheetah control panel is equipped to handle the inputs and outputs required for operating the Micromist system. Factory Mutual Approved heat detectors shall be used in the protected hazard to activate the Micromist system. The piping requirements for the Micromist system offer the flexibility of using galvanized pipe per ASTM A795, stain-less steel tubing or pipe as specified in NFPA 750. Due to the low flow requirements of the Micromist nozzle it is not mandatory that the piping be balanced, which improves system flexibility. Consult the Micromist Design, Installation, and Maintenance Manual (P/N 06-153) for detailed piping limitations. The Micromist system nozzles are constructed of brass and contain a nozzle screen to trap any debris that might be in the system piping. The nozzle utilizes a ½" (15mm) NPT connection and can be easily disassembled to inspect or replace the screen.
The Micromist systems are offered in 70 and 107 gallon (265 and 405 liter) configurations. Each system package is skid-mounted and includes all necessary valves and actuation components for system operation. Each Micromist system package is pre-assembled and tested to ensure system reliability and simplify installation. The Micromist system utilizes relatively short duration’s of water discharges called cycling to aid in the extinguishment of fires. The cycling time for protection of spaces provides enough water for 10 minutes of protection.
In addition to installing a Fike Micromist System, other safeguards should be considered and implemented. Fuel supply shut off to all engines must be provided with a shutoff valve located remote from the engine room. All air movement/ventalization must be shut down.
The Cheetah control panel shall be utilized to handle the inputs and outputs required for a Micromist system. The Cheetah control panel comes equipped to shut down ventilation, shutoff fuel supplies, and other programmable functions to satisfy various needs and operations.
Audible and visual devices are installed to notify personnel of the fire condition. A manual release station is conveniently located to allow personnel electrical manual system operation. The Cheetah control panel relay contacts can be tied into the facility fire alarm system notifying personnel of a trouble or alarm condition. This will ensure proper response in the event of a fire.
Gulf Wide Safety Systems has factory-trained personnel authorized to design, install and provide service for your system requirements. Please call or email for further information.
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